Debugging and common problems

Debugging, Debug and Release configurations

Debugging means finding and fixing errors that cause a program to behave incorrectly. A debugger lets you execute a program step by step and inspect variable values:

1. Set a breakpoint: click in the margin to the left of a line number or press F9. A red dot marks the line.
2. Start debugging with F5. Execution pauses before the line with the breakpoint.
3. Step through the program: F10 (Step Over) moves to the next line, F11 (Step Into) enters a method, Shift+F11 (Step Out) leaves a method, and F5 continues to the next breakpoint.
4. Inspect variable values in Locals (all local variables) and Watch (selected expressions), or hover over a variable in the editor (Fig. 1.27). Press Shift+F5 to stop debugging.

Figure 1.27. Breakpoint and Locals window during debugging

Visual Studio creates two build configurations for a project, selectable in the toolbar list (Fig. 1.28):

• Debug — includes debugging information and does not optimize code; used during development. Output is in bin/Debug/net10.0;
• Release — optimizes code and is intended for the finished application. Output is in bin/Release/net10.0.

Figure 1.28. Selecting a build configuration in the toolbar

To give the program to another user, publish it with dotnet publish -c Release or through Build → Publish Selection in Visual Studio. To run the published program on another computer, the same version of the .NET Runtime must be installed (https://learn.microsoft.com/dotnet/core/deploying/). Visual Studio debugging tools are documented in detail at https://learn.microsoft.com/visualstudio/debugger/ and covered in Topic 6 of this course.

Common beginner problems

Table 1.6 lists problems commonly encountered during the first runs and how to solve them.

Table 1.6. Common problems and solutions

Problem	Cause and solution
The dotnet command is not found (is not recognized)	The SDK is not installed, or the terminal was opened before installation. Open a new terminal and run dotnet --info.
Error NETSDK1045: The current .NET SDK does not support targeting .NET 10.0	An outdated SDK is installed. Install the .NET 10 SDK or update Visual Studio.
? characters appear instead of Ukrainian letters	The encoding has not been set. Add Console.OutputEncoding = System.Text.Encoding.UTF8; at the beginning of the program.
FormatException during int.Parse or double.Parse	The input is not a number or uses a different decimal separator. Use TryParse and check the result.
Error CS8802: Only one compilation unit can have top-level statements	Multiple files contain top-level statements. Keep them only in Program.cs.
The console window closes immediately after launch	The program was started outside the development environment. Run it with Ctrl+F5 or from a terminal.
Console App is missing from the template list	The .NET desktop development workload is not installed. Add it in Visual Studio Installer.